Heat sink



FIG. 1 is a perspective view of a heat sink depicting an embodiment of our new design;

FIG. 2 is an opposite perspective view thereof;

FIG. 3 is a front devotional view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof;

FIG. 7 is a top plan view thereof;

FIG. 8 is a bottom plan view thereof;

FIG. 9 is a perspective view of a heat sink depicting a second embodiment our new design;

FIG. 10 is a front elevational view thereof;

FIG. 11 is a rear elevational view thereof;

FIG. 12 is a left side elevational view thereof;

FIG. 13 is a right side elevational view thereof;

FIG. 14 is a top plan view thereof; and,

FIG. 15 is a bottom plan view thereof.

The broken lines indicate unclaimed portions and form no part of the claimed design. 

CLAIM The ornamental design for a heat sink, as shown and described. 